How to Care for Poinsettias

These tropical plants demand warmth and sun

By Dr. Francis Gouin

A tropical plant that originated in Mexico, the poinsettia is very susceptible to chilling temperatures. If you purchase your plant on a cold day, wrap it completely before moving it from the store to your car. Place it in a sleeve stapled at the top to prevent rapid heat loss and to keep cold air from blowing onto the plant. As soon as you start the car, turn on the heat to a comfortable temperature.
When you arrive at home, the poinsettia should be the first package brought into the house. Allowing the poinsettia to be exposed to temperature below 40 degrees will result in severe drop of both leaves and bracks within a few days.
Most poinsettias are grown with liquid feed in a soil-less medium. Unless you provide some form of fertilizer two to three weeks after purchase, you might see yellowing of the bottom leaves. This is generally a symptom related to nitrogen deficiency. Examine the growing medium of your plant. If small brown or green beads are visible on the surface, it means that the plant has been treated with a slow-release fertilizer and all you need to provide is water to keep it looking healthy. If what you see is white to grey-white granules, that is most likely perlite, which has no nutrient value. You will need to liquid-feed your plant with either fish oil or water-soluble fertilizer to keep it healthy.
Since the poinsettia was grown in a sun-filled greenhouse, you should provide it as much direct sunlight as possible. Placing it near a south-facing window should be your first choice. When expecting guests, move the plant where it can be appreciated by all. Check the plant daily for adequate moisture by pressing your finger into the rooting medium. If it feels cool and moist, there is adequate moisture. If the medium feels warm and dry, add sufficient water so that it drains from the bottom of the container. The roots at the bottom of the container require the same amount of moisture as the roots at the top. Allowing the plant to wilt will shorten display value significantly.
You can also use the bracks and the flowers of the poinsettia in floral arrangements. When the stem is cut, a milky white latex material flows from it. Unless the cut is sealed, the leaves and bracks will wilt. The remedy is to quickly dip the cut end into boiling water so the exposed latex will coagulate, sealing it into the stem but allowing it to absorb water.

Poinsettia Is Not Poisonous
Horticulturists and toxicologists at the University of Kansas proved that neither the stems nor foliage of poinsettias is poisonous. In the research, mice and rats food was progressively supplemented with ground poinsettia leaves and stems, reaching 75 percent poinsettia by volume. The experiment was maintained for one month with no visible side effects. Both species maintained the same level of weight gain as those feed a normal diet. The experiment was repeated for two consecutive years with the same results.
Anecdotally, I have been associated with the Poison Control Center of Maryland for years and have never heard of a case of poinsettia poisoning.

Ask Dr. Gouin your questions at frgouin@erols.com. All questions will appear in Bay Weekly. Please include your name and address.